Coordinated power boost and power back-off

ABSTRACT

A system and method are provided for boosting power for a communications link between a base station and a user device, or user equipment, over a communications link channel in a cellular communications network. In one embodiment, the base station determines whether a communications link for a user device located within a sector of a cell served by the base station needs a power boost. If a power boost is needed, the base station provides a power boost for the communications link for the user device and, for each of one or more neighboring sectors that neighbor the sector in which the user device is located, coordinates the power boost in both frequency and time with a power backoff for a downlink to another user device located in a cell center area of the neighboring sector.

This application is a Continuation of U.S. patent application Ser. No.12/336,844, entitled COORDINATED POWER BOOST AND POWER BACK-OFF, filedDec. 17, 2008, currently pending, which claims the benefit to U.S.Provisional Patent Application Ser. No. 61/188,609, entitled COORDINATEDPOWER BOOST POWER BACK-OFF, filed Aug. 11, 2008 and U.S. ProvisionalPatent Application Ser. No. 61/188,569, entitled SUB CHANNELIZATION WITHPOWER BOOST, filed Aug. 11, 2008, the disclosures of which areincorporated herein by reference in their entireties.

This application claims the benefit of U.S. provisional patentapplication Ser. Nos. 61/188,609 and 61/188,569, both of which werefiled Aug. 11, 2008 and the disclosures of which are hereby incorporatedherein by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to providing a power boost for a wirelesscommunication link.

BACKGROUND OF THE INVENTION

In all cellular communications networks there are opposing requirementsfor high spectrum efficiency and high area availability, or coverage. Asa Fourth Generation (4G) technology, Long Term Evolution (LTE) isexpected to provide high spectrum efficiency. Namely, LTE is expected toprovide three to four times higher spectrum efficiency than High-SpeedDownlink Packet Access (HSDPA) Release 6 for the downlink, and two tothree times higher spectrum efficiency than High-Speed Uplink PacketAccess (HSUPA) Release 6 for the uplink. In addition, as with anycellular communications network, LTE must provide 90%-95% coverage,which is referred to as Carrier Grade of Service (CGoS) for coverage.The requirements for high spectrum efficiency and coverage are opposingin that a small frequency reuse factor (N) is desired in order toachieve high spectrum efficiency but, in general, a high frequency reusefactor (N) is desired in order to decrease out-of-cell interference andtherefore increase coverage. A maximum spectrum efficiency is achievedwhen the frequency reuse factor (N) is 1, such that the entire spectrumis reused in each cell of the cellular communications network. However,when the frequency reuse factor (N) is 1, out-of-cell interference is atits maximum and, therefore, coverage is at its worst.

Spectrum efficiency can be roughly determined by a minimumSignal-to-Interference-plus-Noise (SINR) needed for a wirelesscommunication link, or airlink, to survive in the cellularcommunications network. For example, an Advanced Mobile Phone System(AMPS) typically requires a SINR of greater than or equal to +18decibels (dB). Thus, in order to achieve the CGoS in AMPS, a very largefrequency reuse factor of N=21 is needed in order to achieve the neededSINR. As another example, a Code Division Multiple Access (CDMA) systemcan operate with SINR values as low as −14 dB as a result of theprocessing gain due to the spreading and dispreading process. Therefore,a frequency reuse factor of N=1 can be used in the CDMA system.

For LTE, a minimum SINR needed to maintain a wireless communication linkis approximately −5 dB. However, for a fully loaded LTE network having afrequency reuse factor of N=1, test results show that the SINR at celledges can be lower than −12 dB. Therefore, there is a need for a systemand method for improving coverage in an LTE cellular communicationsnetwork while maintaining high frequency reuse.

SUMMARY OF THE INVENTION

The present invention relates to boosting power for a communicationslink between a base station and a user device, or user equipment, over acommunications link channel in a cellular communications network. In oneembodiment, the communications link is a downlink. The base stationdetermines whether a downlink for a user device located within a sectorof a cell served by the base station needs a power boost. Morespecifically, the base station determines that the downlink needs apower boost if the user device is located in a cell edge area of thecell served by the base station. If a power boost is needed, the basestation provides a power boost for the downlink to the user device and,for each of one or more neighboring sectors that neighbor the sector inwhich the user device is located, coordinates the power boost in bothfrequency and time with a power backoff for a downlink to another userdevice located in a cell center area of the neighboring sector. The oneor more neighboring sectors may be all neighboring sectors inneighboring cells or a subset of all neighboring sectors in theneighboring cells. In addition, the one or more neighboring sectors mayinclude one or more neighboring sectors in the cell in which the userdevice is located. By coordinating the power boost for the user devicewith the power backoffs for the downlinks to the other user deviceslocated in the cell center areas of the one or more neighboring sectors,effects of increased out-of-cell interference resulting from the powerboost are mitigated.

In another embodiment, the communications link is an uplink. The basestation determines whether an uplink for a user device located within asector of a cell served by the base station needs a power boost. Morespecifically, the base station determines that the uplink needs a powerboost if the user device is located in a cell edge area of the cellserved by the base station. If a power boost is needed, the base stationprovides a power boost for the uplink from the user device and, for eachof one or more neighboring sectors that neighbor the sector in which theuser device is located, coordinates the power boost in both frequencyand time with a power backoff for an uplink to another user devicelocated in an cell center area of the neighboring sector. The one ormore neighboring sectors may be all neighboring sectors in neighboringcells or a subset of all neighboring sectors in the neighboring cells.In addition, the one or more neighboring sectors may include one or moreneighboring sectors in the cell in which the user device is located. Bycoordinating the power boost for the user device with the power backoffsfor the uplinks to the other user devices located in the cell centerareas of the one or more neighboring sectors, effects of increasedout-of-cell interference resulting from the power boost are mitigated.

Those skilled in the art will appreciate the scope of the presentinvention and realize additional aspects thereof after reading thefollowing detailed description of the preferred embodiments inassociation with the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawing figures incorporated in and forming a part ofthis specification illustrate several aspects of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1 illustrates a cellular communications network in which basestations provide coordinated power boosts and power backoffs accordingto one embodiment of the present invention;

FIGS. 2A and 2B graphically illustrate a power boost according to oneembodiment of the present invention;

FIGS. 3A and 3B are a flow chart illustrating the operation of a basestation implementing a coordinates power boost and power backoff schemefor a downlink according to one embodiment of the present invention;

FIGS. 4A and 4B are a flow chart illustrating the operation of a basestation implementing a coordinates power boost and power backoff schemefor an uplink according to one embodiment of the present invention;

FIG. 5 is a block diagram of a base station according to one embodimentof the present invention; and

FIG. 6 is a block diagram of a user equipment (UE) according to oneembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments set forth below represent the necessary information toenable those skilled in the art to practice the invention and illustratethe best mode of practicing the invention. Upon reading the followingdescription in light of the accompanying drawing figures, those skilledin the art will understand the concepts of the invention and willrecognize applications of these concepts not particularly addressedherein. It should be understood that these concepts and applicationsfall within the scope of the disclosure and the accompanying claims.

FIG. 1 illustrates a cellular communications network 10 according to oneembodiment of the present invention. In the preferred embodiment, thecellular communications network 10 is a Long Term Evolution (LTE)cellular communications network. However, the present invention is notlimited thereto. The present invention may be utilized in any cell-basedor cellular communications network wherein power boosts are desired inorder to increase coverage while maintaining high spectrum efficiency.In general, the cellular communications network 10 includes a number ofbase stations 12-1 through 12-7 forming corresponding cells 14-1 through14-7 of the cellular communications network 10. The base stations 12-1through 12-7 and the cells 14-1 through 14-7 may generally be referredto herein as base stations 12 and cells 14. Each of the cells 14includes an alpha sector (α), a beta sector (β), and a gamma sector (γ).Note that while only seven base stations 12-1 through 12-7 andcorresponding cells 14-1 through 14-7 are shown for ease of discussion,it will be apparent to one of ordinary skill in the art that thecellular communications network 10 may include any number of basestations 12 and corresponding cells 14. Further, while in thisembodiment each cell 14 includes three sectors, the present invention isnot limited thereto. Each cell 14 may include any number of sectors.

Looking first at cell 14-1, the alpha sector of cell 14-1 includes acell edge area 16-1, a cell middle area 18-1, and a cell center area20-1. Likewise, the beta and gamma sectors of cell 14-1 include celledge areas 16-2 and 16-3, cell middle areas 18-2 and 18-3, and cellcenter areas 20-2 and 20-3, respectively. The cell edge areas 16-1,16-2, and 16-3 of the alpha, beta, and gamma sectors of the cell 14-1are generally referred to herein as a cell edge area 16 of the cell14-1. Likewise, the cell middle areas 18-1, 18-2, and 18-3 of the alpha,beta, and gamma sectors of the cell 14-1 are generally referred toherein as a cell middle area 18 of the cell 14-1, and the cell centerareas 20-1, 20-2, and 20-3 of the alpha, beta, and gamma sectors of thecell 14-1 are generally referred to herein as a cell center area 20 ofthe cell 14-1.

In the preferred embodiment, the cell edge area 16 of the cell 14-1 isan area of the cell 14-1 in which Signal-to-Interference-plus-NoiseRatios (SINRs) for communications links (i.e., uplinks and/or downlinks)between user equipments (UEs) and the base station 12-1 are less than aminimum SINR (SINR_(MIN)). The minimum SINR (SINR_(MIN)) is preferably aminimum SINR needed to maintain an uplink and/or downlink connectionwith the base station 12-1. In an LTE cellular communications network,the minimum SINR (SINR_(MIN)) is approximately −5 decibels (dB). Thecell center area 20 of the cell 14-1 is an area of the cell 14-1 inwhich SINRs for uplinks and/or downlinks between UEs and the basestation 12-1 are greater than a maximum SINR (SINR_(MAX)). The maximumSINR (SINR_(MAX)) is preferably a SINR value at which throughput for theUEs is maximized. For an LTE cellular communications network, themaximum SINR (SINR_(MAX)) is approximately +19 dB forSingle-Input-Single-Output (SISO) UEs. In an LTE cellular communicationsnetwork, when the SINR is +19 dB, the modulation and coding schemeproviding the maximum throughput is used, which is 64 QuadratureAmplitude Modulation (QAM) at a 3/4 coding rate. As such, improvementsto the SINR beyond +19 dB provide no additional throughput. The cellmiddle area 18 of the cell 14-1 is an area of the cell 14-1 in whichSINRs for uplinks and/or downlinks between UEs and the base station 12-1is greater than the minimum SINR (SINR_(MIN)) and less than the maximumSINR (SINR_(MAX)).

The alpha, beta, and gamma sectors of the cell 14-2 include cell edgeareas 22-1, 22-2, and 22-3, cell middle areas 24-1, 24-2, and 24-3, andcell center areas 26-1, 26-2, and 26-3. The cell edge areas 22-1, 22-2,and 22-3, the cell middle areas 24-1, 24-2, and 24-3, and the cellcenter areas 26-1, 26-2, and 26-3 are generally referred to herein as acell edge area 22 of the cell 14-2, a cell middle area 24 of the cell14-2, and a cell center area 26 of the cell 14-2, respectively. Asdiscussed above with respect to the cell 14-1, the cell edge area 22 isan area of the cell 14-2 in which uplinks and/or downlinks to UEs haveSINRs below the minimum SINR (SINR_(MIN)). The cell middle area 24 is anarea of the cell 14-2 in which uplinks and/or downlinks to UEs haveSINRs greater than the minimum SINR (SINR_(MIN)) and less than themaximum SINR (SINR_(MAX)), and the cell center area 26 is an area of thecell 14-2 in which uplinks and/or downlinks to UEs have SINRs greaterthan the maximum SINR (SINR_(MAX)).

The alpha, beta, and gamma sectors of the cell 14-3 include cell edgeareas 28-1, 28-2, and 28-3, cell middle areas 30-1, 30-2, and 30-3, andcell center areas 32-1, 32-2, and 32-3. The cell edge areas 28-1, 28-2,and 28-3, the cell middle areas 30-1, 30-2, and 30-3, and the cellcenter areas 32-1, 32-2, and 32-3 are generally referred to herein as acell edge area 28 of the cell 14-3, a cell middle area 30 of the cell14-3, and a cell center area 32 of the cell 14-3, respectively. Asdiscussed above with respect to the cell 14-1, the cell edge area 28 isan area of the cell 14-3 in which uplinks and/or downlinks to UEs haveSINRs below the minimum SINR (SINR_(MIN)). The cell middle area 30 is anarea of the cell 14-3 in which uplinks and/or downlinks to UEs haveSINRs greater than the minimum SINR (SINR_(MIN)) and less than themaximum SINR (SINR_(MAX)), and the cell center area 32 is an area of thecell 14-3 in which uplinks and/or downlinks to UEs have SINRs greaterthan the maximum SINR (SINR_(MAX)).

The alpha, beta, and gamma sectors of the cell 14-4 include cell edgeareas 34-1, 34-2, and 34-3, cell middle areas 36-1, 36-2, and 36-3, andcell center areas 38-1, 38-2, and 38-3. The cell edge areas 34-1, 34-2,and 34-3, the cell middle areas 36-1, 36-2, and 36-3, and the cellcenter areas 38-1, 38-2, and 38-3 are generally referred to herein as acell edge area 34 of the cell 14-4, a cell middle area 36 of the cell14-4, and a cell center area 38 of the cell 14-4, respectively. Asdiscussed above with respect to the cell 14-1, the cell edge area 34 isan area of the cell 14-4 in which uplinks and/or downlinks to UEs haveSINRs below the minimum SINR (SINR_(MIN)). The cell middle area 36 is anarea of the cell 14-4 in which uplinks and/or downlinks to UEs haveSINRs greater than the minimum SINR (SINR_(MIN)) and less than themaximum SINR (SINR_(MAX)), and the cell center area 38 is an area of thecell 14-4 in which uplinks and/or downlinks to UEs have SINRs greaterthan the maximum SINR (SINR_(MAX)).

The alpha, beta, and gamma sectors of the cell 14-5 include cell edgeareas 40-1, 40-2, and 40-3, cell middle areas 42-1, 42-2, and 42-3, andcell center areas 44-1, 44-2, and 44-3. The cell edge areas 40-1, 40-2,and 40-3, the cell middle areas 42-1, 42-2, and 42-3, and the cellcenter areas 44-1, 44-2, and 44-3 are generally referred to herein as acell edge area 40 of the cell 14-5, a cell middle area 42 of the cell14-5, and a cell center area 44 of the cell 14-5, respectively. Asdiscussed above with respect to the cell 14-1, the cell edge area 40 isan area of the cell 14-5 in which uplinks and/or downlinks to UEs haveSINRs below the minimum SINR (SINR_(MIN)). The cell middle area 42 is anarea of the cell 14-5 in which uplinks and/or downlinks to UEs haveSINRs greater than the minimum SINR (SINR_(MIN)) and less than themaximum SINR (SINR_(MAX)), and the cell center area 44 is an area of thecell 14-5 in which uplinks and/or downlinks to UEs have SINRs greaterthan the maximum SINR (SINR_(MAX)).

The alpha, beta, and gamma sectors of the cell 14-6 include cell edgeareas 46-1, 46-2, and 46-3, cell middle areas 48-1, 48-2, and 48-3, andcell center areas 50-1, 50-2, and 50-3. The cell edge areas 46-1, 46-2,and 46-3, the cell middle areas 48-1, 48-2, and 48-3, and the cellcenter areas 50-1, 50-2, and 50-3 are generally referred to herein as acell edge area 46 of the cell 14-6, a cell middle area 48 of the cell14-6, and a cell center area 50 of the cell 14-6, respectively. Asdiscussed above with respect to the cell 14-1, the cell edge area 46 isan area of the cell 14-6 in which uplinks and/or downlinks to UEs haveSINRs below the minimum SINR (SINR_(MIN)). The cell middle area 48 is anarea of the cell 14-6 in which uplinks and/or downlinks to UEs haveSINRs greater than the minimum SINR (SINR_(MIN)) and less than themaximum SINR (SINR_(MAX)), and the cell center area 50 is an area of thecell 14-6 in which uplinks and/or downlinks to UEs have SINRs greaterthan the maximum SINR (SINR_(MAX)).

The alpha, beta, and gamma sectors of the cell 14-7 include cell edgeareas 52-1, 52-2, and 52-3, cell middle areas 54-1, 54-2, and 54-3, andcell center areas 56-1, 56-2, and 56-3. The cell edge areas 52-1, 52-2,and 52-3, the cell middle areas 54-1, 54-2, and 54-3, and the cellcenter areas 56-1, 56-2, and 56-3 are generally referred to herein as acell edge area 52 of the cell 14-7, a cell middle area 54 of the cell14-7, and a cell center area 56 of the cell 14-7, respectively. Asdiscussed above with respect to the cell 14-1, the cell edge area 52 isan area of the cell 14-7 in which uplinks and/or downlinks to UEs haveSINRs below the minimum SINR (SINR_(MIN)). The cell middle area 54 is anarea of the cell 14-7 in which uplinks and/or downlinks to UEs haveSINRs greater than the minimum SINR (SINR_(MIN)) and less than themaximum SINR (SINR_(MAX)), and the cell center area 56 is an area of thecell 14-7 in which uplinks and/or downlinks to UEs have SINRs greaterthan the maximum SINR (SINR_(MAX)).

In operation, the base stations 12-1 through 12-7 communicate via abackhaul network 58 to coordinate power boosts for communication links(i.e., uplinks and/or downlinks) for UEs in the respective cell edgeareas of the sectors of their own cells with power backoffs forcommunication links for UEs in cell center areas of neighboring sectorsin neighboring cells, thereby extending the coverage of the cellularcommunications network 10. The backhaul network 58 may be a wirednetwork such as an Ethernet or fiber network, a wireless network, or acombination thereof. More specifically, in one embodiment, using thebase station 12-1 as an example, the base station 12-1 monitorscommunication link SINRs for UEs located within the cell 14-1, which inthis example include UEs 60, 62, 64, 66, and 68. UEs, such as the UE 68,having communication link SINRs greater than the minimum SINR(SINR_(MIN)) and less than the maximum SINR (SINR_(MAX)) are located inthe cell middle area 18 of the cell 14-1. As such, the base station 12-1does not provide a power boost or a power backoff for these UEs.

UEs having communication link SINRs less than the minimum SINR(SINR_(MIN)) are located within the cell edge area 16 of the cell 14-1.In this example, the UEs 60, 62, and 64 are located within the cell edgearea 16 of the cell 14-1. In order to improve the communication linkSINRs of the UEs 60, 62, and 64 to a point where communication linksbetween the base station 12-1 and the UEs 60, 62, and 64 can bemaintained, the base station 12-1 provides a power boost for thecommunication links for the UEs 60, 62, and 64. For each of the UEs 60,62, and 64, the amount of power boost is related to a difference betweenthe minimum SINR (SINR_(MIN)) and the communication link SINR for thatUE.

UEs having communication link SINRs greater than the maximum SINR(SINR_(MAX)) are located within the cell center area 20 of the cell14-1. In this example, the UE 66 is located in the cell center area 20of the cell 14-1. Since the UE 66 has a communication link SINR beyondthat which is needed for maximum throughput, the base station 12-1provides a power backoff for the UE 66 such that the total effect of thepower backoff and increased interference resulting from power boosts inneighboring sectors is a communication link SINR for the UE 66 ofapproximately the maximum SINR (SINR_(MAX).

Further, in order to mitigate effects of additional interferenceresulting from the power boosts provided for communication links for UEsin the cell edge area 16 of the cell 14-1 as well as to avoid collisionsof power boosted signals, the base station 12-1 coordinates the powerboosts with power backoffs in neighboring sectors in both frequency andin time. Using the UE 60 as an example, in the preferred embodiment, thebase station 12-1 coordinates the power boost for the communication linkto the UE 60 located in the alpha sector of the cell 14-1 in bothfrequency and in time with a power backoff for a communication link to aUE in the respective cell center areas of each neighboring sector.Therefore, in this embodiment, the base station 12-1 coordinates thepower boost for the communication link to the UE 60 with a power backofffor a communication link to a UE located in the cell center area 26-2 ofthe beta sector of the cell 14-2, a power backoff for a communicationlink to a UE located in the cell center area 26-3 of the gamma sector ofthe cell 14-2, a power backoff for a communication link to a UE in thecell center area 32-3 of the gamma sector of the cell 14-3, and a powerbackoff for a communication link to a UE in the cell center area 56-2 ofthe beta sector of the cell 14-7. In addition, the base station 12-1 maycoordinate the power boost for the UE 60 in both frequency and in timewith a power backoff for a communication link to a UE in the cell centerarea 20-2 of the beta sector of the cell 14-1 and a power backoff for acommunication link to a UE, such as the UE 66, in the cell center area20-3 of the gamma sector of the cell 14-1.

FIGS. 2A and 2B graphically illustrate a power boost according to oneembodiment of the present invention. Before specifically discussingFIGS. 2A and 2B, a description of the downlink and uplink channels isneeded. The downlink channel used by the base stations 12-1 through 12-7has a full channel bandwidth including a number of sub-carrierfrequencies over which data is transmitted. For LTE, the downlinkchannel is an Orthogonal Frequency Division Multiple Access (OFDMA)channel having a full channel bandwidth of 1.25 megahertz (MHz), 2.5MHz, 5 MHz, 10 MHz, 15 MHz, or 20 MHz, depending on the particularimplementation. Within the full channel bandwidth, data is modulated ona number of sub-carrier frequencies. In order to provide downlinks forthe UEs located in the cell 14-1, resource blocks (RBs) within thedownlink channel are allocated to the UEs as needed. A RB is formed bytwelve consecutive sub-carrier frequencies in the frequency domain andfourteen consecutive symbols in the time domain, which corresponds to180 kilohertz (KHz) in the frequency domain and one (1) millisecond(ms), or one (1) sub-frame, in the time domain. In a similar manner, theuplink channel used by the base stations 12-1 through 12-7 has a fullchannel bandwidth including a number of sub-carrier frequencies overwhich data is transmitted. For LTE, the uplink channel is aSingle-Carrier Frequency Division Multiple Access (SC-FDMA) channelhaving a full channel bandwidth of 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, 15MHz, or 20 MHz, depending on the particular implementation. Within thefull channel bandwidth, data is modulated on a number of sub-carrierfrequencies. In order to provide uplinks for the UEs located in the cell14-1, RBs within the uplink channel are allocated to the UEs as needed.

FIG. 2A illustrates a signal power density, thermal noise density, andout-of-cell interference in the full channel bandwidth of the downlinkor the uplink channel without the power boost. As shown, the signalpower density is spread across the full channel bandwidth. FIG. 2Billustrates the signal power density, thermal noise density, andout-of-cell interference after a power boost according to one embodimentof the present invention. Using the base station 12-1 and the UE 60 asan example, in order to provide a power boost for a downlink to the UE60, the base station 12-1 provides a reduced bandwidth channel that is asub-channel of the downlink channel. In other words, the reducedbandwidth channel is formed by a subset of the sub-carrier frequenciesof the downlink channel. Further, the bandwidth of the reduced bandwidthchannel is a portion of the full bandwidth of the downlink channel. Thedownlink to the UE 60 is provided by allocating one or more RBs in thereduced bandwidth channel for the downlink to the UE 60. By using thereduced bandwidth channel for the downlink to the UE 60 while keepingthe signal power or transmit power constant, the signal power density isconcentrated on the reduced channel bandwidth rather than spread acrossthe full bandwidth of the downlink channel. The signal power densityconcentration provides a power boost for the downlink to the UE 60. Inthe same manner, a power boost may be provided for an uplink to the UE60. Note that while FIG. 2B illustrates the reduced bandwidth channel asbeing a number of consecutive or contiguous sub-carrier frequencies, thepresent invention is not limited thereto. The sub-carrier frequenciesforming the reduced bandwidth channel may be one or more contiguoussub-carrier frequencies, one or more non-contiguous sub-carrierfrequencies, or a combination thereof.

By concentrating the signal power density, the SINR per sub-carrierfrequency, or the SINR per tone, is substantially increased as comparedto the SINR of the full bandwidth channel. Specifically, a SINRper-channel (SINR_(CHANNEL)) is defined as:

${{SINR}_{CHANNEL} = \frac{P_{{FULL\_ CHANNEL}{\_ BW}}}{{Interference}_{{FULL\_ CHANNEL}{\_ BW}} + {{Thermal}\_{Noise}}_{{FULL\_ CHANNEL}{\_ BW}}}},$where P_(FULL) _(—) _(CHANNEL) _(—) _(BW) is the total signal powerwithin the full channel bandwidth, Interference_(FULL) _(—) _(CHANNEL)_(—) _(BW) is the total interference within the full channel bandwidth,and Thermal_Noise_(FULL) _(—) _(CHANNEL) _(—) _(BW) is the thermal noisepower within the full channel bandwidth. The SINR per sub-carrierfrequency, or SINR per tone, (SINR_(TONE)) is defined as:

${{SINR}_{TONE} = \frac{P_{TONE\_ BW}}{{Interference}_{TONE\_ BW} + {{Thermal}\_{Noise}}_{TONE\_ BW}}},$where P_(TONE) _(—) _(BW) is the total signal power within the bandwidthof the tone, Interference_(TONE) _(—) _(BW) is the total interferencewithin the bandwidth of the tone, and Thermal_Noise_(TONE) _(—) _(BW) isthe thermal noise power within the bandwidth of the tone. When thesignal power is uniformly spread across the full bandwidth as shown inFIG. 2A, the SINR per-channel (SINR_(CHANNEL)) is equal to the SINR pertone (SINR_(TONE)). In contrast, when the signal power is concentratedon a reduced bandwidth channel as shown in FIG. 2B, the SINR per tone(SINR_(TONE)) is defined as:SINR_(TONE)=SINR_(CHANNEL)+Power_Boost,where Power_Boost is a gain [dB] resulting from the concentration of thesignal power in the reduced bandwidth channel. In general, the powerboost is related to a ratio of the full channel bandwidth and thereduced channel bandwidth of the reduced bandwidth channel.Specifically, the power boost may be defined as:

${{Power}\_{Boost}} = {10 \cdot {{{\log_{10}\left( \frac{{{full}\_{channel}}{\_{bandwidth}}}{{{reduced}\_{channel}}{\_{bandwidth}}} \right)}\lbrack{dB}\rbrack}.}}$

FIGS. 3A and 3B are a flow chart illustrating the operation of a basestation implementing a coordinated power boost and power backoff schemefor a downlink according to one embodiment of the present invention. Forthis discussion, the base station is the base station 12-1 of FIG. 1.However, this discussion is equally applicable to the other basestations 12-2 through 12-7 in the cellular communications network 10.First, the base station 12-1 obtains a downlink SINR from a UE (step100). In one embodiment, for an LTE cellular communications network, thebase station 12-1 sends a request to the UE instructing the UE to reporta Channel Quality Index (CQI) to the base station 12-1, where the CQIincludes the downlink SINR for the UE. In response, the UE reports theCQI to the base station 12-1.

The base station 12-1 then determines whether the downlink SINR for theUE is greater than the minimum SINR (SINR_(MIN)) and less than themaximum SINR (SINR_(MAX)) (step 102). In other words, the base station12-1 determines whether the UE is located in the cell middle area 18 ofthe cell 14-1. If so, the base station 12-1 schedules a downlink to theUE using the downlink channel having the full channel bandwidth using aproper Modulation and Coding Scheme (MCS) at a full transmit power level(step 104). More specifically, for an LTE cellular communicationsnetwork, the base station 12-1 selects the proper MCS for the UE basedon the downlink SINR for the UE. Further, the full transmit power levelmay be a maximum transmit power of the base station 12-1 or apredetermined backoff from the maximum transmit power of the basestation 12-1. The base station 12-1 schedules the downlink to the UE byallocating one or more sub-carrier frequencies during one or moretransmit time intervals (TTIs) for the downlink to the UE. For an LTEcellular communications network, the base station 12-1 schedules thedownlink to the UE by allocating one or more RBs for the downlink to theUE. The process then returns to step 100 and is repeated.

Returning to step 102, if the downlink SINR for the UE is not greaterthan the minimum SINR (SINR_(MIN)) and less than the maximum SINR(SINR_(MAX)) (i.e., if the UE is not located in the cell middle area 18of the cell 14-1), the base station 12-1 determines whether the downlinkSINR is greater than the maximum SINR (SINR_(MAX)) (step 106). In otherwords, the base station 12-1 determines whether the UE is located in thecell center area 20 of the cell 14-1. If so, in this embodiment, thebase station 12-1 determines whether the UE is a SISO device (step 108).Note that, for an LTE cellular communications network,Multiple-Input-Multiple-Output (MIMO) devices may have improvedthroughput even as the downlink SINR increases above the maximum SINR(SINR_(MAX)), which for LTE is approximately +19 dB. If the UE is not aSISO device, the base station 12-1 schedules the downlink to the UEusing the downlink channel having the full channel bandwidth using aproper MCS at the full transmit power level (step 110). The base station12-1 schedules the downlink to the UE by allocating one or moresub-carrier frequencies during one or more TTIs for the downlink to theUE. For an LTE cellular communications network, the base station 12-1schedules the downlink to the UE by allocating one or more RBs for thedownlink to the UE. The process then returns to step 100 and isrepeated.

Returning to step 108, if the UE is a SISO device, the base station 12-1schedules the downlink to the UE using the downlink channel having thefull channel bandwidth using a proper MCS at a reduced transmit powerlevel, thereby providing a power backoff for the downlink to the UE(step 112). More specifically, the base station 12-1 schedules thedownlink to the UE by allocating one or more sub-carrier frequenciesduring one or more TTIs for the downlink to the UE. For an LTE cellularcommunications network, the base station 12-1 schedules the downlink tothe UE by allocating one or more RBs for the downlink to the UE.Further, in selecting the sub-carrier frequencies and TTI(s) orselecting RBs to allocate for the downlink to the UE, the base station12-1 may consider information regarding power boosts and power backoffsin neighboring sectors of a sector within the cell 14-1 in which the UEis located that has been reported by the corresponding base stations viathe backhaul network 58 (FIG. 1). For example, if the UE is located inthe alpha sector of the cell 14-1, the base station 12-1 may considerinformation regarding power boosts and power backoffs reported from theneighboring sectors of the alpha sector of the cell 14-1, which are thebeta and gamma sectors of the cell 14-2, the gamma sector of the cell14-3, and the beta sector of the cell 14-7. The information regardingpower boosts and power backoffs preferably includes informationidentifying the sub-carrier frequencies or RB sub-carrier frequencygroups on which power boosts are currently being provided by the basestations 12-2, 12-3, and 12-7 in the neighboring sectors and the amountof power boost for each of those sub-carrier frequencies or RBsub-carrier frequency groups. In addition, the information regardingpower boosts and power backoffs preferably includes informationidentifying the sub-carrier frequencies or RB sub-carrier frequencygroups on which power backoffs are currently being provided by the basestations 12-2, 12-3, and 12-7 in the neighboring sectors and the amountof power backoff for each of those sub-carrier frequencies or RBsub-carrier frequency groups. In addition, the base station 12-1 mayconsider information regarding power boosts and power backoffs in theneighboring sectors within the cell 14-1.

Once the downlink is scheduled, the base station 12-1 notifies the otherbase stations 12-2 through 12-7 of the sub-carrier frequencies or the RBsub-carrier frequency groups scheduled for use for the downlink to theUE via the backhaul network 58 (step 114). For an LTE cellularcommunications network, the base station 12-1 notifies the other basestations 12-2 through 12-7 using X2 messages. Specifically, the basestation 12-1 communicates a low interference state for the selectedsub-carrier frequencies or the RB sub-carrier frequency groups scheduledfor the downlink to the UE via a Relative Narrowband Transmit (Tx) Power(RNTP) indicator. At this point, the process returns to step 100 and isrepeated.

Returning to step 106, if the downlink SINR for the UE is not greaterthan the maximum SINR_(MAX), the UE is located in the cell edge area 16of the cell 14-1. As such, a power boost is needed. In this embodiment,in order to provide the power boost, the base station 12-1 first obtainssub-band SINRs for each sub-band in the downlink channel from the UE(step 116). In one embodiment, for an LTE cellular communicationsnetwork, the base station 12-1 sends a request to the UE for sub-bandCQIs for the downlink channel. In response, the UE sends the sub-bandCQIs, which include the sub-band SINRs, to the base station 12-1.

Next, the base station 12-1 identifies a subset of the sub-carrierfrequencies of the downlink channel for a reduced bandwidth channelbased on reported power boost and power backoff information forneighboring sectors such that the reduced bandwidth channel has areduced bandwidth that is sufficient to provide a desired power boost(step 118). More specifically, in selecting the sub-carrier frequenciesor RB sub-carrier frequency groups for the reduced bandwidth channel,the base station 12-1 considers information regarding power boosts andpower backoffs in neighboring sectors of a sector in which the UE islocated that has been reported by the corresponding base stations viathe backhaul network 58 (FIG. 1). Thus, for example, if the UE islocated in the alpha sector of the cell 14-1, the base station 12-1considers information regarding power boosts and power backoffs reportedfrom the neighboring sectors of the alpha sector of the cell 14-1, whichare the beta and gamma sectors of the cell 14-2, the gamma sector of thecell 14-3, and the beta sector of the cell 14-7. The informationregarding power boosts and power backoffs preferably includesinformation identifying the sub-carrier frequencies or RB sub-carrierfrequency groups on which power boosts are currently being provided bythe base stations 12-2, 12-3, and 12-7 in the neighboring sectors andthe amount of power boost for each of those sub-carrier frequencies orRB sub-carrier frequency groups. In addition, the information regardingpower boosts and power backoffs preferably includes informationidentifying the sub-carrier frequencies or RB sub-carrier frequencygroups on which power backoffs are currently being provided by the basestations 12-2, 12-3, and 12-7 in the neighboring sectors and the amountof power backoff for each of those sub-carrier frequencies or RBsub-carrier frequency groups. In addition, the base station 12-1 mayconsider information regarding power boosts and power backoffs in theneighboring sectors within the cell 14-1.

Based on the information regarding power boosts and power backoffs inneighboring sectors, the base station 12-1 is enabled to selectsub-carrier frequencies or RB sub-carrier frequency groups for thereduced bandwidth channel such that the power boost for the downlink tothe UE is coordinated with power backoffs in neighboring sectors.Specifically, in one embodiment, the base station 12-1 selectssub-carrier frequencies or RB sub-carrier frequencies for the reducedbandwidth channel that, according to the power boost and power backoffinformation, are: (1) currently being used for a power backoff in eachof the neighboring sectors and (2) are not currently being used byanother neighboring sector for a power boost. Then, using at least asubset of the selected sub-carrier frequencies or RB sub-carrierfrequencies, the base station 12-1 provides the reduced bandwidthchannel having a reduced channel bandwidth that is sufficiently reducedas compared to the full channel bandwidth of the downlink channel toprovide the desired power boost.

In the preferred embodiment, the power boost is coordinated with a powerbackoff in each neighboring sector in another cell and, optionally, eachneighboring sector in the same cell. However, coordination of the powerboost with a power backoff in each of the neighboring sectors may not bepossible in either of two situations. The first situation is where oneor more of the neighboring sectors do not have any UEs located in theircell center areas for which sub-carrier frequencies or RB sub-carrierfrequencies are currently being used at a power backoff. The secondsituation is where one or more of the neighboring sectors do not haveany more sub-carrier frequencies or RB sub-carrier frequency groups thatare currently being used for a power backoff and are not already beingused for a power boost in another neighboring sector. In either of thesesituations, rather than coordinating the power boost with a powerbackoff, the base station 12-1 may coordinate the power boost to avoid acollision with a power boosted signal from a neighboring sector.Specifically, based on the power boost and the power backoff informationreported for the neighboring sectors, the base station 12-1 is enabledto determine which sub-carrier frequencies or which RB sub-carrierfrequency groups are already being used for power boosts in neighboringsectors. The base station 12-1 may then select other sub-carrierfrequencies or other RB sub-carrier frequency groups for the reducedbandwidth channel.

In one embodiment, the desired power boost is a difference between theminimum SINR (SINR_(MIN)) and the downlink SINR for the UE. This isparticularly beneficial in a coverage limited situation, or noiselimited situation, where the out-of-cell interference is much less thanthermal noise (I<<n). In a coverage limited situation, the SINRimprovement or gain for the UE resulting from an X dB power boost is XdB. In another embodiment, the desired power boost is SINR_(MIN) minusthe downlink SINR for the UE minus the amount of power backoff for thesub-carrier frequencies or the RB sub-carrier frequency groups withwhich the power boost is coordinated. This is particularly beneficial inan interference limited situation where the out-of-cell interference ismuch greater than the thermal noise (I>>n). In an interference limitedsituation, the SINR improvement or gain for the UE resulting from an XdB power boost coordinated with a Y dB power backoff is X+Y dB.

The bandwidth of the reduced bandwidth channel is indirectly related tothe desired amount of power boost. In one embodiment, the reducedchannel bandwidth may be determined based on the following equation:

${{Power}\_{Boost}} = {10 \cdot {{\log_{10}\left( \frac{{{full}\_{channel}}{\_{bandwidth}}}{{{reduced}\_{channel}}{\_{bandwidth}}} \right)}.}}$As such,

${{{reduced}\_{channel}}{\_{bandwidth}}} = {\frac{{{full}\_{channel}}{\_{bandwidth}}}{10^{\frac{Power\_ Boost}{10}}}.}$Thus, for example, if the desired power boost is 4.77 dB persub-carrier, then the reduced channel bandwidth is ⅓ of the full channelbandwidth.

Next, the base station 12-1 schedules the downlink for the UE in thereduced bandwidth channel on sub-carrier frequencies or RB sub-carrierfrequency groups that are currently experiencing low amount or a leastamount of out-of-cell interference (step 120). More specifically, basedon the sub-band SINRs obtained in step 116, the base station 12-1 mayidentify sub-carrier frequencies or RB sub-carrier frequency groupshaving sub-band SINRs that are greater than a threshold value and thenselect M of those sub-carrier frequencies or RB sub-carrier frequencygroups, where M corresponds to a number of sub-carrier frequencies orRBs to be allocated for the downlink to the UE. In another embodiment,the base station 12-1 may select M sub-carrier frequencies or RBsub-carrier frequency groups having the highest sub-band SINRs, whereagain M corresponds to the number of sub-carrier frequencies or RBsub-carrier frequency groups to be allocated for the downlink to the UE.Then, the selected sub-carrier frequencies or RB sub-carrier frequencygroups are allocated for the downlink to the UE during one or more TTIs.

The base station 12-1 notifies the other base stations 12-2 through 12-7of the sub-carrier frequencies or RB sub-carrier frequency groupsscheduled for use for the downlink to the UE via the backhaul network 58(step 122). For an LTE cellular communications network, the base station12-1 notifies the other base stations 12-2 through 12-7 using X2messages. Specifically, the base station 12-1 communicates a highinterference state for the selected sub-carrier frequencies or RBsub-carrier frequency groups scheduled for the downlink to the UE viathe RNTP indicator. At this point, the process returns to step 100 andis repeated.

Note that in LTE, the shortest RNTP update period is 200 ms. As such, atmost, the RNTP indicator can be updated every 200 ms. However, becausethe power boost and power backoff situations in the cells 14-1 through14-7 will most likely change within this 200 ms period, the base station12-1 may reuse sub-carrier frequencies used for a power boost for one ormore additional power boosts during the 200 ms period. For example, ifthe base station 12-1 allocates a particular RB sub-carrier frequencygroup for a power boost for the downlink to the UE, the downlink to theUE may no longer be needed if the base station 12-1 has no more data tosend to the UE. If this occurs within the 200 ms RNTP update period, thebase station 12-1 may reuse the RB sub-carrier frequency group foranother power boost of an equal or lesser amount. If no such power boostis needed, then the base station 12-1 will not schedule the RBsub-carrier frequency group until the next RNTP update is received. In asimilar manner, sub-carrier frequencies used for a power backoff may bereused during the 200 ms RNTP update period for one or more additionalpower backoffs of equal or less amount.

FIGS. 4A and 4B are a flow chart illustrating the operation of a basestation implementing a coordinated power boost and power backoff schemefor an uplink according to one embodiment of the present invention. Forthis discussion, the base station is the base station 12-1 of FIG. 1.However, this discussion is equally applicable to the other basestations 12-2 through 12-7 in the cellular communications network 10.First, the base station 12-1 obtains an uplink SINR for a UE (step 200).In one embodiment, the base station 12-1 measures the uplink SINR forthe UE. The base station 12-1 then determines whether the uplink SINRfor the UE is greater than the minimum SINR (SINR_(MIN)) and less thanthe maximum SINR (SINR_(MAX)) (step 202). In other words, the basestation 12-1 determines whether the UE is located in the cell middlearea 18 of the cell 14-1. If so, the base station 12-1 schedules theuplink to the UE using an uplink channel having the full channelbandwidth using a proper MCS at a full transmit power level (step 204).More specifically, for an LTE cellular communications network, the basestation 12-1 selects the proper MCS for the UE based on the uplink SINRfor the UE. Further, the full transmit power level may be a maximumtransmit power of the UE or a predetermined power backoff from themaximum transmit power of the UE. The base station 12-1 schedules theuplink from the UE by allocating one or more sub-carrier frequenciesduring one or more TTIs for the uplink to the UE. For an LTE cellularcommunications network, the base station 12-1 schedules the uplink fromthe UE by allocating one or more RBs for the uplink to the UE. Theprocess then returns to step 200 and is repeated.

Returning to step 202, if the uplink SINR for the UE is not greater thanthe minimum SINR (SINR_(MIN)) and less than the maximum SINR(SINR_(MAX)) (i.e., if the UE is not located in the cell middle area 18of the cell 14-1), the base station 12-1 determines whether the uplinkSINR is greater than the maximum SINR (SINR_(MAX)) (step 206). In otherwords, the base station 12-1 determines whether the UE is located in thecell center area 20 of the cell 14-1. If so, in this embodiment, thebase station 12-1 determines whether the UE is a SISO device (step 208).Note that, for an LTE cellular communications network, MIMO devices mayhave improved throughput even as the uplink SINR increases above themaximum SINR (SINR_(MAX)), which for LTE is approximately +19 dB. If theUE is not a SISO device, the base station 12-1 schedules the uplink tothe UE using the uplink channel having the full channel bandwidth usinga proper MCS at the full transmit power level (step 210). The basestation 12-1 schedules the uplink to the UE by allocating one or moresub-carrier frequencies during one or more TTIs for the uplink to theUE. For an LTE cellular communications network, the base station 12-1schedules the uplink to the UE by allocating one or more RBs for theuplink to the UE. The process then returns to step 200 and is repeated.

Returning to step 208, if the UE is a SISO device, the base station 12-1schedules the uplink to the UE using the uplink channel having the fullchannel bandwidth using a proper MCS at a reduced transmit power level,thereby providing a power backoff for the uplink from the UE (step 212).More specifically, the base station 12-1 schedules the uplink to the UEby allocating one or more sub-carrier frequencies during one or moreTTIs for the uplink to the UE. For an LTE cellular communicationsnetwork, the base station 12-1 schedules the uplink to the UE byallocating one or more RBs for the uplink to the UE. Further, inselecting the sub-carrier frequencies and TTI(s) or selecting RBs toallocate for the uplink to the UE, the base station 12-1 may considerinformation regarding power boosts and power backoffs in neighboringsectors of a sector within the cell 14-1 in which the UE is locatedreported by the corresponding base stations via the backhaul network 58(FIG. 1). For example, if the UE is located in the alpha sector of thecell 14-1, the base station 12-1 may consider information regardingpower boots and power backoffs reported from the neighboring sectors ofthe alpha sector of the cell 14-1, which are the beta and gamma sectorsof the cell 14-2, the gamma sector of the cell 14-3, and the beta sectorof the cell 14-7. The information regarding power boosts and powerbackoffs preferably includes information identifying the sub-carrierfrequencies or RB sub-carrier frequency groups on which power boosts arecurrently being provided by the base stations 12-2, 12-3, and 12-7 inthe neighboring sectors and the amount of power boost for each of thosesub-carrier frequencies or RB sub-carrier frequency groups. In addition,the information regarding power boosts and power backoffs preferablyincludes information identifying the sub-carrier frequencies or RBsub-carrier frequency groups on which power backoffs are currently beingprovided by the base stations 12-2, 12-3, and 12-7 in the neighboringsectors and the amount of power backoff for each of those sub-carrierfrequencies or RB sub-carrier frequency groups. In addition, the basestation 12-1 may consider information regarding power boosts and powerbackoffs in the neighboring sectors within the cell 14-1.

Once the uplink is scheduled, the base station 12-1 notifies the otherbase stations 12-2 through 12-7 of the sub-carrier frequencies or RBsub-carrier frequency groups scheduled for use for the uplink to the UEvia the backhaul network 58 (step 214). For an LTE cellularcommunications network, the base station 12-1 notifies the other basestations 12-2 through 12-7 using X2 messages. Specifically, the basestation 12-1 communicates a low interference state for the selectedsub-carrier frequencies or RB sub-carrier frequency groups scheduled forthe uplink to the UE via via an LTE High-Interference Indicator (HII) oran LTE Overload Indicator (OI). At this point, the process returns tostep 200 and is repeated.

Returning to step 206, if the uplink SINR for the UE is not greater thanthe maximum SINR_(MAX), the UE is located in the cell edge area 16 ofthe cell 14-1. As such, a power boost is needed. In this embodiment, inorder to provide the power boost, the base station 12-1 first determinesan amount of out-of-cell interference for each sub-carrier frequency orRB sub-carrier frequency group in the uplink (step 216). In oneembodiment, the base station 12-1 measures the out-of-cell interferenceper RB sub-carrier frequency group using the LTE OI.

Next, the base station 12-1 identifies a subset of the sub-carrierfrequencies of the uplink channel for a reduced bandwidth channel basedon reported power boost and power backoff information for neighboringsectors such that the reduced bandwidth channel has a reduced bandwidththat is sufficient to provide a desired power boost (step 218). Morespecifically, in selecting the sub-carrier frequencies or RB sub-carrierfrequency groups for the reduced bandwidth channel, the base station12-1 considers information regarding power boosts and power backoffs inneighboring sectors of a sector in which the UE is located that has beenreported by the corresponding base stations via the backhaul network 58(FIG. 1). Thus, for example, if the UE is located in the alpha sector ofthe cell 14-1, the base station 12-1 considers information regardingpower boosts and power backoffs reported from the neighboring sectors ofthe alpha sector of the cell 14-1, which are the beta and gamma sectorsof the cell 14-2, the gamma sector of the cell 14-3, and the beta sectorof the cell 14-7. The information regarding power boosts and powerbackoffs preferably includes information identifying the sub-carrierfrequencies or RB sub-carrier frequency groups on which power boosts arecurrently being provided by the base stations 12-2, 12-3, and 12-7 inthe neighboring sectors and the amount of power boost for each of thosesub-carrier frequencies or RB sub-carrier frequency groups. In addition,the information regarding power boosts and power backoffs preferablyincludes information identifying the sub-carrier frequencies or RBsub-carrier frequency groups on which power backoffs are currently beingprovided by the base stations 12-2, 12-3, and 12-7 in the neighboringsectors and the amount of power backoff for each of those sub-carrierfrequencies or RB sub-carrier frequency groups. In addition, the basestation 12-1 may consider information regarding power boosts and powerbackoffs in the neighboring sectors within the cell 14-1.

Based on the information regarding power boosts and power backoffs inneighboring sectors, the base station 12-1 is enabled to selectsub-carrier frequencies or RB sub-carrier frequency groups for thereduced bandwidth channel such that the power boost for the uplink fromthe UE is coordinated with power backoffs in neighboring sectors.Specifically, in one embodiment, the base station 12-1 selectssub-carrier frequencies or RB sub-carrier frequencies for the reducedbandwidth channel that, according to the power boost and power backoffinformation, are: (1) currently being used for a power backoff in eachof the neighboring sectors and (2) are not currently being used byanother neighboring sector for a power boost. Then, using at least asubset of the selected sub-carrier frequencies or RB sub-carrierfrequencies, the base station 12-1 provides the reduced bandwidthchannel having a reduced channel bandwidth that is sufficiently reducedas compared to the full channel bandwidth of the uplink channel toprovide the desired power boost.

In the preferred embodiment, the power boost is coordinated with a powerbackoff in each neighboring sector in another cell and, optionally, eachneighboring sector in the same cell. However, coordination of the powerboost with a power backoff in each of the neighboring sectors may not bepossible in either of two situations. The first situation is where oneor more of the neighboring sectors do not have any UEs located in theircell center areas for which sub-carrier frequencies or RB sub-carrierfrequencies are currently being used for a power backoff. The secondsituation is where one or more of the neighboring sectors do not haveany more sub-carrier frequencies or RB sub-carrier frequency groups thatare currently being used for a power backoff and are not already beingused for a power boost in another neighboring sector. In either of thesesituations, rather than coordinating the power boost with a powerbackoff, the base station 12-1 may coordinate the power boost to avoid acollision with a power boosted signal from a neighboring sector.Specifically, based on the power boost and power backoff informationreported for the neighboring sectors, the base station 12-1 is enabledto determine which sub-carrier frequencies or which RB sub-carrierfrequency groups are already being used for power boosts in neighboringsectors. The base station 12-1 may then select other sub-carrierfrequencies or RB sub-carrier frequency groups for the reduced bandwidthchannel.

In one embodiment, the desired power boost is a difference between theminimum SINR (SINR_(MIN)) and the uplink SINR for the UE. This isparticularly beneficial in a coverage limited situation, or noiselimited situation, where the out-of-cell interference is much less thanthermal noise (I<<n). In a coverage limited situation, the SINRimprovement or gain for the UE resulting from an X dB power boost is XdB. In another embodiment, the desired power boost is SINR_(MIN) minusthe uplink SINR for the UE minus the amount of power backoff for thesub-carrier frequencies or RB sub-carrier frequency groups with whichthe power boost is coordinated. This is particularly beneficial in aninterference limited situation where the out-of-cell interference ismuch greater than the thermal noise (I>>n). In an interference limitedsituation, the SINR improvement or gain for the UE resulting from an XdB power boost coordinated with a Y dB power backoff is X+Y dB.

The bandwidth of the reduced bandwidth channel is indirectly related tothe desired amount of power boost. In one embodiment, the reducedchannel bandwidth may be determined based on the following equation:

${{Power}\_{Boost}} = {10 \cdot {{\log_{10}\left( \frac{{{full}\_{channel}}{\_{bandwidth}}}{{{reduced}\_{channel}}{\_{bandwidth}}} \right)}.}}$As such,

${{{reduced}\_{channel}}{\_{bandwidth}}} = {\frac{{{full}\_{channel}}{\_{bandwidth}}}{10^{\frac{Power\_ Boost}{10}}}.}$Thus, for example, if the desired power boost is 4.77 dB persub-carrier, then the reduced channel bandwidth is ⅓ of the full channelbandwidth.

Next, the base station 12-1 schedules the uplink for the UE in thereduced bandwidth channel on sub-carrier frequencies or RB sub-carrierfrequency groups that are currently experiencing a low amount, or aleast amount, of out-of-cell interference (step 220). More specifically,based on the out-of-cell interference measured in step 216, the basestation 12-1 may identify sub-carrier frequencies or RB sub-carrierfrequency groups having out-of-cell interference that is less than athreshold value and then select M of those sub-carrier frequencies or RBsub-carrier frequency groups, where M corresponds to a number ofsub-carrier frequencies or RBs to be allocated for the uplink to the UE.In another embodiment, the base station 12-1 may select M sub-carrierfrequencies or RB sub-carrier frequency groups having the lowestout-of-cell interference, where again M corresponds to the number ofsub-carrier frequencies or RB sub-carrier frequency groups to beallocated for the uplink to the UE. Then, the selected sub-carrierfrequencies or RB sub-carrier frequency groups are allocated for theuplink to the UE during one or more TTIs.

The base station 12-1 notifies the other base stations 12-2 through 12-7of the sub-carrier frequencies or RB sub-carrier frequency groupsscheduled for use for the uplink to the UE via the backhaul network 58(step 222). For an LTE cellular communications network, the base station12-1 notifies the other base stations 12-2 through 12-7 using X2messages. Specifically, the base station 12-1 communicates a highinterference state for the selected sub-carrier frequencies or RBsub-carrier frequency groups scheduled for the downlink to the UE viathe LTE HII or the LTE OI. At this point, the process returns to step200 and is repeated.

FIG. 5 is a block diagram of an exemplary embodiment of the base station12-1 of FIG. 1. However, this discussion is equally applicable to theother base stations 12-2 through 12-7 in the cellular communicationsnetwork 10. In general, the base station 12-1 includes a control system70 having associated memory 72. In addition, in this embodiment, thebase station 12-1 includes sector transceivers 74-1, 74-2, and 74-3 forthe alpha, beta, and gamma sectors of the cell 14-1 (FIG. 1),respectively. The functionality of the base station 12-1 discussed abovefor providing power boosts may be implemented in hardware forming partof the control system 70, software stored in the memory 72, or acombination thereof.

FIG. 6 is a block diagram of the UE 60 of FIG. 1. This discussion isequally applicable to other UEs in the cellular communications network10. In general, the UE 60 includes a control system 76 having associatedmemory 78. In addition, the UE 60 includes a cellular communicationsinterface 80. The functionality of the UE 60 discussed above withrespect to power boosting may be implemented within a protocol stack ofthe cellular communications interface 80 implemented in software storedin the memory 78, or a combination thereof. The UE 60 may also include auser interface 82, which may include components such as, for example,one or more user input devices (e.g., microphone, keypad, or the like),one or more speakers, a display, or the like.

Those skilled in the art will recognize improvements and modificationsto the preferred embodiments of the present invention. All suchimprovements and modifications are considered within the scope of theconcepts disclosed herein and the claims that follow.

What is claimed is:
 1. A method of operating a base station in acommunications network, comprising: determining whether a power boost isdeemed desirable for a first communications link between the basestation and a first user device served by the base station in a firstserving area of the base station; and when a power boost is deemeddesirable for the first communications link between the base station andthe user device, providing a power boost that is coordinated both infrequency and in time with a power back-off for a second communicationslink to a second user device served in a second serving area, the secondserving area being a neighbor to the first serving area.
 2. The methodof claim 1, wherein the first serving area and the second serving areaare neighboring cell sectors.
 3. The method of claim 1, wherein a powerboost is deemed desirable for the first communications link when aSignal-to-Interference-plus-Noise Ratio (SINR) for the firstcommunications link is less than a first threshold SINR.
 4. The methodof claim 3, wherein the power back-off is applied to the secondcommunications link when a SINR for the second communications link isgreater than a second threshold SINR.
 5. The method of claim 1 furthercomprising: when a power boost is deemed desirable for the firstcommunications link, providing a power boost that is coordinated both infrequency and time with power back-offs for a plurality of othercommunications links, each of the plurality of other communication linksbeing linked to a respective other device served in at least one otherserving area of a plurality of other serving areas, each of the at leastone other serving area being a neighbor to the first serving area. 6.The method of claim 5, wherein the power back-off is applied to arespective other communications link to another user device when arespective SINR for the respective other communications link is greaterthan a threshold SINR.
 7. The method of claim 5, wherein: the firstcommunications link has a full channel bandwidth comprising a pluralityof sub-carrier frequencies; and providing a power boost for the firstcommunications link comprises: identifying a subset of the plurality ofsub-carrier frequencies of the first communications link as a reducedbandwidth channel for the first communications link based on informationregarding power boosts and power back-offs in the plurality of otherserving areas such that the reduced bandwidth channel has a reducedbandwidth that is less than the full channel bandwidth of the firstcommunications link channel; and scheduling the first communicationslink using the reduced bandwidth channel such that signal power isconcentrated on the subset of the plurality of sub-carrier frequenciesin the reduced bandwidth channel.
 8. The method of claim 7, wherein theinformation regarding power boosts and power back-offs in the pluralityof other serving areas comprises information identifying sub-carrierfrequencies from the plurality of sub-carrier frequencies of thecommunications links used for power boosts in the plurality of otherserving areas, and information identifying sub-carrier frequencies fromthe plurality of sub-carrier frequencies of the communications linksused for power back-offs in the plurality of other serving areas.
 9. Themethod of claim 8, wherein the subset of the plurality of sub-carrierfrequencies comprises sub-carrier frequencies from the plurality ofsub-carrier frequencies that are being used for a power back-off in eachof the plurality of other serving areas and are not being used for apower boost in any of the plurality of other serving areas.
 10. Themethod of claim 7, further comprising determining an amount ofout-of-serving-area interference for each of the subset of the pluralityof sub-carrier frequencies, wherein: scheduling the first communicationslink using the reduced bandwidth channel comprises allocating at leastone sub-carrier frequency from the subset of the plurality ofsub-carrier frequencies in the reduced bandwidth channel having a leastamount of out-of-serving-area interference.
 11. The method of claim 10,further comprising notifying neighboring base stations of the schedulingof the first communications link.
 12. The method of claim 7, furthercomprising notifying neighboring base stations of the scheduling of thefirst communications link.
 13. A base station for a communicationsnetwork, comprising: at least one transceiver operable to providecommunications links to user devices located within a serving area ofthe base station; and a control system associated with the at least onetransceiver operable to: determine whether a power boost is deemeddesirable for a first communications link between the base station and afirst user device served by the base station in a first serving area ofthe base station; and when a power boost is deemed desirable for thefirst communications link between the base station and the user device,provide a power boost that is coordinated both in frequency and in timewith a power back-off for a second communications link to a second userdevice served in a second serving area, the second serving area being aneighbor to the first serving area.
 14. The base station of claim 13,wherein the first serving area and the second serving area areneighboring cell sectors.
 15. The base station of claim 13, wherein thecontrol system is operable to deem desirable a power boost for the firstcommunications link when a Signal-to-Interference-plus-Noise Ratio(SINR) for the first communications link is less than a first thresholdSINR.
 16. The base station of claim 15, wherein the control system isoperable to apply the power back-off to the second communications linkwhen a SINR for the second communications link is greater than a secondthreshold SINR.
 17. The base station of claim 13, wherein when a powerboost is deemed desirable for the first communications link, the controlsystem is operable to provide a power boost that is coordinated both infrequency and time with power back-offs for a plurality of othercommunications links, each of the plurality of other communication linksbeing linked to a respective other device served in at least one otherserving area of a plurality of other serving areas, each of the at leastone other serving area being a neighbor to the first serving area. 18.The base station of claim 17, wherein the control system is operable toapply the power back-oft to a respective other communications link toanother user device when a respective SINR for the respective othercommunications link is greater than a threshold SINR.
 19. The basestation of claim 17, wherein: the first communications link has a fullchannel bandwidth comprising a plurality of sub-carrier frequencies; andthe control system is operable to provide a power boost for the firstcommunications link by: identifying a subset of the plurality ofsub-carrier frequencies of the first communications link as a reducedbandwidth channel for the first communications link based on informationregarding power boosts and power back-offs in the plurality of otherserving areas such that the reduced bandwidth channel has a reducedbandwidth that is less than the full channel bandwidth of the firstcommunications link channel; and scheduling the first communicationslink using the reduced bandwidth channel such that signal power isconcentrated on the subset of the plurality of sub-carrier frequenciesin the reduced bandwidth channel.
 20. The base station of claim 19,wherein the information regarding power boosts and power back-offs inthe plurality of other serving areas comprises information identifyingsub-carrier frequencies from the plurality of sub-carrier frequencies ofthe communications links used for power boosts in the plurality of otherserving areas, and information identifying sub-carrier frequencies fromthe plurality of sub-carrier frequencies of the communications linksused for power back-offs in the plurality of other serving areas. 21.The base station of claim 20, wherein the subset of the plurality ofsub-carrier frequencies comprises sub-carrier frequencies from theplurality of sub-carrier frequencies that are being used for a powerback-oft in each of the plurality of other serving areas and are notbeing used for a power boost in any of the plurality of other servingareas.
 22. The base station of claim 20, wherein the control system isfurther operable to notify neighboring base stations of the schedulingof the first communications link.
 23. The base station of claim 19,wherein the control system is operable to: determine an amount ofout-of-serving-area interference for each of the subset of the pluralityof sub-carrier frequencies; and schedule the first communications linkusing the reduced bandwidth channel by allocating at least onesub-carrier frequency from the subset of the plurality of sub-carrierfrequencies in the reduced bandwidth channel having a least amount ofout-of-serving-area interference.
 24. The base station of claim 19,wherein the control system is further operable to notify neighboringbase stations of the scheduling of the first communications link.
 25. Amethod of operating a base station in a communications network,comprising: determining whether a power back-off is deemed desirable fora first communications link between the base station and a first userdevice served by the base station in a first serving area of the basestation; and when a power back-off is deemed desirable for the firstcommunications link between the base station and the user device,scheduling the first communications with the power back-off andnotifying a base station serving a second serving area of the schedulingof the first communications link.
 26. The method of claim 25, whereinthe first serving area and the second serving area are neighboring cellsectors.
 27. The method of claim 25, wherein a power back-off is deemeddesirable for the first communications link when aSignal-to-Interference-plus-Noise Ratio (SINR) for the firstcommunications link is greater than a first threshold SINR.
 28. Themethod of claim 27, wherein a power boost is applied to a secondcommunications link when a SINR for the second communications link isless than a second threshold SINR.
 29. The method of claim 25 furthercomprising: when a power back-off is deemed desirable for the firstcommunications link, scheduling the first communications with the powerback-off and notifying a plurality of other base stations servingrespective other serving areas of the scheduling of the firstcommunications link, each of the respective other serving areas being aneighbor to the first serving area.
 30. A base station for acommunications network, comprising: at least one transceiver operable toprovide communications links to user devices located within a servingarea of the base station; and a control system associated with the atleast one transceiver operable to: determine whether a power back-off isdeemed desirable for a first communications link between the basestation and a first user device served by the base station in a firstserving area of the base station; and when a power back-off is deemeddesirable for the first communications link between the base station andthe user device, schedule the first communications with the powerback-off and to notify a base station serving a second serving area ofthe scheduling of the first communications link.
 31. The base station ofclaim 30, wherein the first serving area and the second serving area areneighboring cell sectors.
 32. The base station of claim 30, wherein thecontrol system is operable to deem desirable a power back-off for thefirst communications link when a Signal-to-Interference-plus-Noise Ratio(SINR) for the first communications link is greater than a firstthreshold SINR.
 33. The base station of claim 32, wherein the controlsystem is operable to apply a power boost to a second communicationslink when a SINR for the second communications link is less than asecond threshold SINR.
 34. The base station of claim 30, wherein when apower back-off is deemed desirable for the first communications link,the control system is operable to schedule the first communications withthe power back-off and to notify a plurality of other base stationsserving respective other serving areas of the scheduling of the firstcommunications link, each of the respective other serving areas being aneighbor to the first serving area.